JPS6111919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid phase epitaxial growth method and a growth apparatus therefor.

Recent improvements in liquid phase epitaxial growth technology have led to dramatic improvements in yield and reliability of devices such as semiconductor lasers. Even in the grown film thickness,
It has become possible to easily create thin films of 0.1 μm or less, and to control the film thickness with high precision.

Currently, liquid phase epitaxial growth methods include a horizontal slide method and a vertical rotation method. The horizontal slide method is a method in which a substrate and multiple solution tanks are arranged horizontally and in a straight line, and the substrate or solution tanks are brought into contact with each other one by one by pushing, and is the most commonly used method due to its simple operation. Sufficient soaking length is required. In addition, the vertical rotation method is a method in which a substrate and multiple solution tanks are placed on the same circumference and brought into contact with each other one by one by rotating the substrate or solution tank. The temperature distribution only needs to be within one cross section of the circular furnace, and it is very easy to obtain a uniform temperature distribution, but as the substrate size increases and the number of solution baths increases, it is necessary to increase the size of the circular furnace. . In either case, there are advantages and disadvantages, but
The same level of crystal growth layer was obtained in all cases under strict control of usage conditions.

However, with this conventional growth method,
Since only one wafer can be grown at one time, mass production is difficult, and the use of solvent and solute in the solution bath is extremely uneconomical.

The present invention uses a horizontal slide method or a vertical rotation method to bring two or more substrates into contact with one solution at the same time and slide or rotate them sequentially, thereby growing two or more wafers in a single crystal growth process. can be produced.

Hereinafter, the crystal growth method of the present invention will be described in detail with reference to Examples and drawings.

Note that since both the horizontal slide method and the vertical rotation method are the same in principle regarding the present invention, the horizontal slide method will be explained here.

FIG. 1 is a sectional view of a carbon boat used in a conventional horizontal slide system. A growth substrate 2 is set in the groove of the substrate holder 1, and a solution 4 consisting of various solvents and solutes is set in each tank of the solution holder 3 as shown in FIG. After the temperature is raised, the temperature is maintained at a constant temperature so that the solvent in the solution 4 is sufficiently dissolved and stirred uniformly, and then the temperature is lowered at a constant cooling rate to start growth. For growth, a multilayer film is obtained by pushing the quartz rod 5 and sequentially bringing the solutions 4 in each tank into contact with the growth substrate 2. The quartz rod 6 is for fixing the substrate holder 1. In general, semiconductor lasers and the like formed by liquid phase epitaxial growth have a double heterostructure formed by such a method. However, only one grown wafer can be obtained by one crystal growth, which is inefficient and not suitable for mass production. In order to achieve mass production, it is necessary to grow several wafers at the same time.

The purpose of the present invention is to simultaneously grow a plurality of wafers and achieve mass production. Figures 2a to 2d show a cross-sectional view of the growth process using the carbon boat (for two-wafer growth) of the present invention. show. Figure a shows the state before the temperature starts to decrease, with two growth substrates 2
are set in the groove of the substrate holder 1 and on the growth solution holder 8. The solution holder 3 in Fig. 1 corresponds to the growth solution holder 8 in Fig. 2.
and a solution auxiliary holder 9. Another feature of this boat is that each tank of the solution auxiliary holder 9 is filled with the solution 4, whereas the growth solution holder 8 only has the solution 4 in the separate tank, as shown in Figure 2b. , first, use the quartz rod 5 to hold the solution auxiliary holder 9.
When the is slid as shown in the figure, the solution 4 in the auxiliary holder 9 is dropped into the waste liquid tank 11 through the empty tank of the growth solution holder 8. Furthermore, when the tank of the auxiliary solution holder 9 is slid until the empty tank of the growth solution holder 8 coincides with each other, the carbon block 10 is also dropped into the waste liquid tank 11 next to the solution 4 in the auxiliary holder 9. At this time, the upper surfaces of the substrate holder 1 and the carbon block 10 are made flat as shown in FIG. 2c. Next, from the state shown in the figure c, the growth solution holder 8 is
Press to slide between the substrate holder 1 and the solution auxiliary holder 9. Growth solution holder 8
The solution filled in the tank is brought into contact with the two growth substrates 2 sandwiched above and below by the slide as shown in FIG. 2d, and the two substrates are grown simultaneously. Furthermore, by sliding the growth solution holder 8 and sequentially bringing them into contact, two multilayer film growth wafers can be obtained.

The characteristics of the crystal growth method using carbon boats as described above will be described. The first feature, as mentioned above, is that two wafers can be grown simultaneously, which is very efficient. This is an effective method for mass production. The second feature is that the thickness of the ultra-thin film can be easily controlled. The thickness of the grown film depends not only on the growth initiation temperature, degree of supercooling, cooling rate, and growth time, but also on the thickness of the solution. When the thickness of the solution is increased, the growth becomes very fast, and it becomes difficult to control even a film thickness of about 0.2 μm. In addition, when the thickness of the solution is reduced to 1 mm or less, the growth rate decreases significantly, 0.1
Even growth layers of micrometers or less can be obtained with good reproducibility. However, if the thickness of the solution is set to 1 mm or less from the beginning, the solvent in the solution will not be sufficiently stirred as a whole, resulting in a non-uniform layer. Therefore, before starting growth, use as thick a solution as possible, and after making the entire solution uniform in composition,
The best method is to dilute the solution. According to the present invention, before the start of growth, a thick solution is prepared in the tanks of the growth solution holder 8 and the solution auxiliary holder 9, and after the solution is made uniform, the growth solution holder 8
Only the solution in the tank is used for growth. The thickness of the growth solution holder 8 can be made arbitrarily; if this thickness is set to 2 mm, the solution in this tank will also be 2 mm, but since there are two substrates above and below the solution, and growth is occurring on both at the same time, Generally speaking, it can be considered as a 1 mm solution. In this case, as mentioned above, a grown layer of 0.1 μm or less can be obtained with good reproducibility, so it is ideal for growing active layers of semiconductor lasers.
In the case of thick film growth, the thickness of the growth solution holder 8 may be increased.

Although the above-mentioned embodiment was a method of growing two wafers, in the case of the present invention, it is also possible to grow three wafers. As shown in FIG. 3, a new substrate holder 12 is placed under the waste liquid tank 11, and by sliding this substrate holder 12, the substrate holder 12 is sequentially brought into contact with the solution in the waste liquid tank 11 to cause growth. According to this method, three wafers can be grown in parallel, making it a more efficient crystal growth method.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a carbon boat used in conventional liquid phase growth, Figures 2 a to d are process diagrams showing the liquid phase growth method of the present invention, and Figure 3 is a diagram of another liquid phase growth apparatus of the present invention. It is a sectional view showing an example. 1... Substrate holder, 2... Growth substrate, 3...
...Solution holder, 4...Solution, 5...Quartz rod, 6
...Fixing quartz rod, 7...Quartz rod for growth solution holder, 8...Growth solution holder, 9...Solution auxiliary holder, 10...Carbon block, 11
...Waste liquid tank, 12...Substrate holder.

Claims (1)

[Scope of Claims] 1. A substrate holder having a waste liquid tank and a substrate holder, an auxiliary solution holder having a solution discharge through hole and a solution growth through hole, and a main solution holder having a solution holding portion. Using a liquid phase epitaxial growth apparatus that is slidable relative to each other, the solution holding part and the solution growth through hole are aligned, the growth solution is filled into the solution growth through hole, and then the solution holding part is filled with a growth solution. and the solution discharge through-hole and the waste liquid tank are aligned to discharge the growth solution in the solution holding section to the waste liquid tank, and then the solution growth through-hole and the substrate holding section are aligned and the A liquid phase epitaxial growth method characterized by bringing a growth solution in a solution growth through-hole into contact with a substrate. 2. A substrate holder having a waste liquid tank and a substrate holder, an auxiliary solution holder having a solution discharge through hole and a solution growth through hole, and a main solution holder having a solution holding part, the solution holding part and the through-hole for solution growth match, a state where the solution holding part, the through-hole for solution discharge, and the waste liquid tank match, and a state where the through-hole for solution growth and the substrate holding part match. The liquid phase epitaxial growth apparatus is characterized in that the substrate holder, the auxiliary solution holder, and the main solution holder are installed so as to be able to slide relative to each other so that a state in which the auxiliary solution holder and the main solution holder are slidable relative to each other.